Flexible Web Out-of-plane Vibration Distribution Measurement Based On Extraction Of Structured Light Centerline

With the rapid development of flexible electronic,the R2 R technology has been widely concerned as the key of its batch preparation.In order to improve the production efficiency of flexible electronics,it is necessary to increase as much as possible the velocity while controlling the tension of the web.However,some disturbances limit the production efficiency,like the non-circularity of roll,roll misalignment and web sliding,etc.The fluctuation and uneven distribution of web tension will cause web vibrations,wrinkle,and even breakage.Among them,out-of-plane vibration and its distribution change wiil affect the location,deformation and stability of the patterning process.In this paper,as the urgent demand of out-of-plane vibration distribution measurement of flexible web,a measuring scheme and device for measuring the vibration distribution of web are both designed based on the extraction algorithm of structured light centerline.The main work includes:(1)A measuring scheme for detecting out-of-plane vibration distribution of flexible web is proposed.Based on the structured light vision system,the mathematical model of vibration measurement system is esta?blished and the model is optimized.The relationship between the out-of-plane displacements of moving web and the coordinates of the laser stripe centerline in the images is built.What's more,the hardware selection is carried out according to the actual working condition.(2)A new algorithmic framework is proposed to obtain accurate coordinates of stripe centerline on the moving web.Based on principal component analysis,the processing of image gray space is converted to the processing of image gradient space.The gradient vectors' covariance matrix is solved so that the normal directions of the stripe cross section are obtained.The accurate coordinates of stripe finally are obtained with the improved gray centroid method.Experiments are conducted to confirm the effectiveness and accuracy of the proposed method.(3)A model of binocular vision out-of-plane vibration distribution measurement is proposed.In view of the shortcomings of the monocular vision system,the complex model of the traditional binocular vision is simplified by using stereo calibration and Bouguet stereo rectification,and a random vibration distribution measurement model is built by the principle of parallax.Calibration experiments and rectification experiments are carried out.(4)Experiments are carried to measure the out-of-plane vibration distribution of the moving web.With the measuring scheme and the new algorithmic framework,the vibration amplitude and frequency of flexible web under different conditions are detected and are compared with the free vibration frequency under the theoretical string model.Experiments are carried to prove the effectiveness of measuring system.In summary,the measuring scheme and device proposed in this paper can detect the out-of-plane vibration distribution of moving web in axial direction and it has high precision and high efficiency.In addition,this measuring system is expected to expand to other similar application technologies and fields.